Amomum villosum extract alleviates diabetic neuropathy via phosphoinositide 3-kinase/AKT-mediated antioxidative and anti-apoptotic effects

Abstract

BACKGROUND

Diabetic peripheral neuropathy (DPN) affects nearly half of patients with diabetes and is projected to increase substantially as the diabetes prevalence rises globally. Current treatments remain largely symptomatic with limited efficacy in halting disease progression. Amomum villosum Lour. (AVL), a traditional Chinese medicinal herb with anti-inflammatory and antioxidant properties, represents a potential new therapeutic candidate for DPN management.

AIM

To explore the therapeutic effects of the aqueous extract of AVL on DPN in rats and its underlying molecular mechanisms.

METHODS

A type 1 diabetic rat model was induced by streptozotocin. Pain thresholds were assessed using paw withdrawal threshold and paw withdrawal latency. Primary dorsal root ganglion (DRG) neurons were extracted and cultured to detect indicators related to oxidative stress, inflammatory response, and apoptosis. The therapeutic effects of AVL on DPN rats were evaluated using Western blotting, quantitative PCR, enzyme-linked immunosorbent assay, reactive oxygen species (ROS) content detection, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and flow cytometry. The molecular mechanisms of AVL in inhibiting oxidative stress and apoptosis via the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway were also explored.

RESULTS

AVL treatment significantly counteracted the elevated blood glucose and reduced body weight in diabetic rats. The mechanical and thermal pain thresholds were significantly increased, indicating AVL's analgesic effects. In the diabetes mellitus (DM) + AVL group, the expression of inflammatory cytokines [tumor necrosis factor alpha, interleukin 6 (IL-6), IL-1β] and malondialdehyde content in DRG tissue were lower than those in the DM + vehicle group. However, compared with the DM + vehicle group, the glutathione level was increased in the DM + AVL group. Consistently, immunofluorescence showed that the fluorescence intensity representing ROS in primary DRG neurons was also significantly reduced compared with the DM + vehicle group. In addition, flow cytometry and TUNEL assays revealed that AVL treatment markedly decreased the apoptosis rate of DRG neurons, as evidenced by downregulated caspase-3 and B-cell lymphoma 2 (Bcl-2)-associated X protein expression and upregulated Bcl-2 expression, indicating that AVL also inhibits DRG neuronal apoptosis. Further mechanistic studies demonstrated that AVL treatment activated the PI3K/AKT signaling pathway in DRG neurons. However, intervention with the PI3K inhibitor LY294002 significantly reversed the therapeutic effects of AVL on DNP rats. Mechanistically, AVL activated the PI3K/AKT signaling pathway, suppressing oxidative stress and apoptosis in the DRG tissue of DNP rats.

CONCLUSION

AVL alleviates DNP in rats by activating the PI3K/AKT signaling pathway, inhibiting oxidative stress and apoptosis and reducing inflammatory responses. This study provides strong experimental evidence for the application of AVL in DNP treatment and offers new ideas and directions for the development of DNP treatments based on natural medicines.

Keywords: Amomum villosum Lour.; Diabetic peripheral neuropathy; phosphoinositide 3-kinase/AKT; Oxidative stress; Apoptosis

Core Tip: Diabetic peripheral neuropathy (DPN) lacks effective therapies beyond symptomatic relief. This study demonstrates that the aqueous extract of Amomum villosum Lour. (AVL) significantly alleviates DPN in rats by activating the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway. AVL reduced oxidative stress, inflammation, and neuronal apoptosis in dorsal root ganglion tissues, thereby improving pain thresholds. Inhibition of PI3K/AKT abrogated these protective effects. These findings highlight AVL as a promising natural medicine with multi-targeted neuroprotective properties and provide mechanistic evidence for its potential application in DPN treatment.